Process of distilling mineral oil under a. high vacuum



Oct. 14, 1930. A. E. PEWJR 1,778,555

PROCESS OF DISTILLING MINERAL OIL UNDER A HIGH VACUUM Filed Feb. 27,1926 Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE ARTHUR E. FEW,m, IBBYN HAWK, PENNSYLVANIA, 8161103 '10 SUN OIL (X)!- rm, 0]PHILADELPHIA, PENNSYLVANIA, A CORPORATION 01 PENNSYLVANIA.

PROCESS OI DISTILIIN'G MINERAL OIL UNDER A. HIGH VACUUI Applicationfiled February 27, 1928. Serial ll'o. 81,048.

In an application filedby meJune 19, 1925, Serial No. 38,184, of whichthis application is in part a continuation, I set forth an apparatus forthe continuous distillation of oil 5 under a high vacuum. Included inthe apparatus is a series of stills. These stills and the rest of theoil and oil vapor system are under a high vacuum. It is essential thatthere shall be no leakage whatever into this system. The success of theprocess depends not merely on the maintenance of the vacuum at apredetermined.- degree. If this could sufiice, continuously acting airpumps would maintain the vacuum notwithstanding slight air leakage intothe system. It is important, however, to'prevent'any circulation of evenextremely rarified air through the system, which circulation could occurin case of any leakage. The vacuumair pumps should be relied upon,therefore, only to exhaust air from the system at the start of theprocessand to continuously exhaust from the system permanent gases thatform during the distilling process and which, if allowed to accumulate,2 would build up pressure, but which, to the extent that they arepresent and circulate through the system, do not have the objectionableoxidizing effect of air.

This 'air tight closure of the oil system may be efiected in part bymaking air tight all joints, valves, removable covers, and bearings; butunless some means be devised to prevent it, the oil that is pumped fromthe source of supply to the first still of the series will carry with itsome. air. The object of the invention forming the subject matter ofthis application is to prevent air being pumped in with the oil.

In the drawings, which show a preferred embodiment of the invention-Fig. 1 is a diagram of the first still of the series and the means forsupplying oil thereto.

1 Fig. 2 is a detail view of the pressure regulating valve of Fig. 1.

The still tank a, having a residual oil outlet w and oil va or outlets yto a'condenser z, is supplied with oil from the supply pipe 12. On theipe b is a. valve 0 which regulates the rate of How of oil to the-still.A meter d and 50 a pump e are interposed in the pipe I).

Around the pump is a shunt circuit pipe f provided with a pressurerelief va ve g, which is shown in detail in F ig.- 2. This valve,however, may be of any lmown or convenient construction. It is set toopen at any superatmospheric pressure desired.

When the pump e is first started, valve 0 is closed, thus forcing theoil around the pump through the return pipe f and immediately buildingup a pressure sufiicient to open valve g. Valve 0 is now opened untilthe meter indicates the rate of flow desired. Pump e continuouslydelivers oil at a higher rate of flow than the flow through valve 0,thereby maintaining circulation through pipe f and holding the pressurethat has been built up.

With a constant superatmospheric pressure in the pipe line and with theoil at the source of supplyv at atmospheric pressure, no air can bedrawn with the oil, through the pipe 6 into tank -a.

ITNLhat I claims: 1 1 f e process 0 supp ying o1 rom a source of supplyto a still under high vacuum while preventing the admission of air withthe oil, which comprises pumping oil from a source of supply to thestill at a rate constantly exceeding the rate at which it is desired todeliver oil to the still, so throttling the flow of oil from the pump tothe still as to maintaina substantially constant rate of flow of oil tothe still constantly below the rate at which the oil is pumpedmaintaining in the supply pipe between said point of throttling and thepump a pressure constantly above the pressure between the pump and thesource.

of sup ly, maintaining a constant return flow of oil from a pointbetween the pump and the point of throttling to a point in the oil suply behind the pump, and regulating t 0 pressure in the oil supplybetween the pump and the point of throttlmg by varying the rate of saidreturn flow of 011.

